1. Field of the Invention
The present invention relates to a method for controlling semiconductor processing equipment and, more particularly, to a method for controlling semiconductor processing equipment in real time based on measured data.
2. Description of the Related Art
A semiconductor device is typically fabricated through a large number of unit processes executed in sequence. Accordingly, a large number of sophisticated pieces of equipment, such as sputtering equipment and etching equipment, are disposed along a semiconductor processing line to perform the sequence of unit processes. FIG. 1 is a flowchart of a conventional method for controlling such semiconductor processing equipment.
Referring to FIG. 1, semiconductor processing equipment are controlled by determining whether or not unit processes are being performed using the optimal process settings for each. Optimal settings are determined by measuring characteristic values of a product produced after several processes and comparing those characteristic values to characteristic values and corresponding equipment settings saved in a database of a host computer. The measurements and settings data are displayed on a monitor of an operator interface (O/I), for example a personal computer (PC), in real time. Then, using a computer program run, for example, from the O/I PC, it is determined whether or not the proper settings were applied to the product by comparing the displayed measurement data with initially set optimal settings data. If it is determined that the product is defective, the product is reprocessed or discarded, and appropriate action is taken to repair or reset the equipment to solve problems in the unit processes themselves.
However, the conventional method for controlling the processing equipment suffers from several problems. The measurements are only displayed in real time at the O/I, not analyzed in real time. When an error is detected as a result of the analysis, the detection usually occurs after a series of several unit processes have been performed in sequence. Therefore, the operator has to trace back through several pieces of equipment to determine in which piece of equipment and during which process the error occurred. Thus, a series of appropriate but time consuming actions have to be taken with the equipment to isolate and solve problems in the equipment. Accordingly, even with the real time display of measurements and data used by the conventional method, it takes a great amount of time to analyze the measured data to detect a faulty unit process and to take the corrective action to reset or repair the malfunctioning equipment. As a result, the faulty process may continue to be performed on many products using the malfunctioning equipment during the time the analysis is performed and before the error is corrected. Thus a large number of defective products are produced that have to be reprocessed or discarded, causing waste and reducing the productivity of the processing line.
In addition, the conventional method does not detect faulty processes in advance of a defective product, and thus can not prevent the production of any defective products. The faulty process may be due to an improper setting as a result of a mistake by an engineer, or the faulty process may be due to the equipment's own hardware problems. In either case, several lots, each including a plurality of wafers, are continuously processed with the faulty process, leading to a large number of non-optimal products. This continues undetected until the defective products are finally produced and measured. Then, as a result of the time-consuming analysis, even more time is lost until the defective products are detected and the problem is isolated and corrective action is taken.